Method of making pile yarns



Patented Mar. 7, 1950 METHOD OF MAKING PILE YARNS Robert C. Allison,Ytmkers, N. Y., asslgnor to Alexander Smith & Sons Carpet Company,Yonkers, N. Y., a corporation of New York No Drawing. Application August14, 1945, Serial No. 610,883

' g Claims. 1 This invention relates to pile fabrics intended for hardwear and wherein the pile is cut and formed from pile yarns that havesufliciently high plying twists to impart a knobby or curly texture tothe cut pile as contrasted to the soft plush-like appearance of cut pileobtained from pile yarns with low plying twists. More particularly, itrelates to floor coverings and upholstery fabrics wherein the cut pileis formed from highly twisted yarns of stock dyed wool and in which thetwist is fast to withstand aqueous treatments, such as commercialshampooing, and to the method of producing such pile yarns.

Hard twist frieze carpets and rugs have been woven from pile yarnsthathave sufliciently high plying twists to give a knobby or curly textureto a cut p le as contrasted t the soft plush-like appearance of a cutpile obtained from pile yarn of low plying twists. Floor coveringshaving high twist piles possess many advantages over floor coveringshaving low twist pile. These hard twist frieze carpets and rugs havebeen particularly spun and given a hard twist. Since wool is an elasticmaterial, if the twist were not set prior to weaving, it would unwindwhen the tufts were cut popular in plain colors and have attainedconsiderable commercial success in this country, especially during thepast decade or so. The highly twisted pile has a higher resistance tocrushing than low twist pile. Consequently, in floor coverings having ahighly twisted pile, footprints do not show and shaded areas ofcontrasting appear-' ance do not develop as readily where the trafllcand wear are concentrated as in the case of floor coverings having lowtwist piles. The high twist binds the fibers more tightly in the yarns,thereby reducing shedding and flufling to a minimum. For equalquantities of pile yarn, floor coverings having highly twisted pilespossess a somewhat higher resistance to abrasive wear than floorcoverings having low twist piles.

In one of the methods most generally employed in the production of largeyardages of plain shade carpet free from color streaks and bands and ofuniform shade, loose wool is dyed prior to the carding, spinning andtwisting processes of woolen yarn manufacture. This process of dyeingthe loose wool is known in the art as "stock dyeing, and by suchprocedure very large quantities of wool can be dyed and thoroughlyblended prior to yarn manufacture so that the resulting yarn is veryuniform in color and of sufficient amountto supply numerous looms of allwidths. This enables large lots of carpet of uniform shade to beproduced in many widths and constructions, free from streaks and colorbands, and which can be laid side by side without color contrast.

After the wool has been stock dyed, it is carded,

to form the cut pile. Accordingly, after producing the highly twistedpile yarns and prior to weaving, it has been common practice to set thetwist by steaming the highly twisted yarn with dry steam in cottage"steamers at a few pounds pressure for times ranging up to several hours.In such procedure, the moisture content of the yarn was in equilibriumwith the atmospheric relative humidity and contained from approximately6% to 10% of moisture.

During a floor coverings service, it becomes dirty or soiled. One of themost common-procedures for cleaning a floor covering is by shampooing.In a commercial shampooing the floor covering is placed on a cementfloor. with the pile down, and the back hosed with water. The back isthen scrubbed with a power-driven rotary brush, a gel soap being fedonto the back during this operation. Thereafter, the back is hosed withcold water to remove the soap (rinsing).

.The floor covering is reversed and the foregoing operations performedin the same sequence on the pile face. Finally, the fabric is passedbetween squeeze rollers and dried.

- Floor coverings in which the pile is formed from highly twisted yarnin which the twist was set by dry steaming as above described do notpossess an adequate fastncss of twist to aqueous treatments, such ascommercial shampooing above described. As a result, when such floorcoverings were shampooed by commercial cleaners, the pile lost aconsiderable amount of twist and the cleaned floor coverings lost theiroriginal texture and virtually all of the characteristics of a. highlytwisted yarn. The inadequate twist-set fastness to aqueous treatmentalso has resulted in widespread consumer dissatisfaction, in many claimsand complaints against manufacturers, and has been a problem ofconsiderable magnitude to commercial rug cleaners. The latter haveresorted to certain expedients, as surface cleaning methods usingsolvents, solvent-impregnated powders, or using froths which wet onl thesurface of the pile. These techniques do not thoroughly cleanse thewhole fabric as does the usual rug shampooingwprocedure and thereforegive the consumer a choice of two evils, i. e. poor cleansing or loss ofthe original texture. In some cases, the twist fastness obtained by theprior art procedure previously mentioned has been so poor as to allowsubstantial twist loss from spillage or wet footwear. H

An object of this invention is to provide a highly twisted pile yarn ofstock dyed wool which, when formed into a cut'pile of a pile fabric,possesses improved properties.

Another object of this invention is to provide a highly twisted pileyarn of stock dyed wool and which, when formed into a cut pile of a pilefabric, will be substantially fast to aqueous treatments.

A further object of this invention is to provide a method of makinghighly twisted pile yarn of stock dyed wool whereby, when said yarnconstitutes the cut pile in a pile fabric, the twist will besubstantially fast to aqueous treatments.

Other and additional objects will become apparent hereinafter.

The objects of the invention are accomplished, in general, by forming ahighly twisted stock dyed wool yarn containing preferably at least 30%,by weight, of moisture and setting the twist by steaming with saturatedsteam whereby the moisture content in the yarn is maintained atpreferably at least 30% during the steaming operation.

In the preferred embodiment of the invention, at some stage in theprocess subsequent to stock dyeing of the wool and prior to the twistsetting operation, the yarn is neutralized or rendered alkaline, i. e.the pH of the stock dyed wool is adjusted to approximately 6 to 8, oreven up to 10.

Optimum results, i. e. fastness of the twist to a degree that the pilewill successfully withstand multiple commercial shampooing withoutserious loss of twist, are obtained when after the neutralized highlytwisted yarn has been subjected to steaming at highmo sture levels suchyarn is treated with an aldehyde.

The details and manner of practicing the invent on will become apparentby reference to the followingspecific examples, it being understood thatthese examples areimerely illustrative em-- bodiments of the inventionand that the scope of the claims is not limited thereto.

Example I The wool which is to be formed into the pile yarn is opened upand scoured in the usual manner. Thereafter, the wool is dyed in a knownacid dye bath at a pH of 4.2. At the end of the dyeing o eration, the pHof the wool will be in the neighborhood of 4.2. The dyed wool is sprayedwith a mineral oil emulsion, and various lots thereof are blended tomake a large lot of uniform shade. The wool is carded and spun on thewoolen system to give a singles woolen yarn weighing 207 grains per 50yards with 1'75 turns of the S-twist per yard. Two of such singles yarnsare plied together to form a two-ply yarn, the plying twist being 350turns per yard Z-twist and the weight of the plied yarn being 456 grainsper 50 yards. The plied yarn is neutralized by treatment with analkaline substance, such as an aqueous solution containing 0.5% sodiumcarbonate, whereby the pH of the yarn is adjusted to approximately 6.5.After washing the yarn with .water, it is centrifuged to a substantiallyuniform moisture content of 35%, by weight. The highly twisted yarncontaining 35% moisture is steamed for 2 hours at 220 F. in a closed"cottage steamer with saturated steam whereby the moisture content ofthe yarn is maintained at substantially 35%. I

The pile yarns are then woven into floor coverings by any of thewell-known procedures for producing floor coverings with cut piles.

Example II The procedure is the same as in Example I, except that theyarn containing 35% moisture is steamed with saturated steam for 1 hourat 220 F. in the closed cottage" steamer and the moisture content of theyarn is maintained at substantially 35% during steaming. The steamedyarn is then soaked in a 4% aqueous solution of formaldehyde at F. for 3hours. Upon removal from the formaldehyde solution, the yarn is rinsedtwice with cold water, extracted, and finally dried.

The pile yarns are then woven into a fabric as described in Example I.

The invention can be used with any of the wools or blends of woolcommonly used in the production of pile yarns for carpets, rugs andupholstery fabrics. Wools of the cross-bred types, such as SouthAmerican B. A., South American Cordova, South American Montevideo, NewZealand fleece and English Devon, are comparatively easy to set, whilecarpet type wools, such as India Vicaneer, India Sind and Iraq Awassi,have been found difiicult to. set. In the preferred embodiment of theinvention, a blend comprising 40% to 75% of cross-bred wools and 60% to25% of carpet wools, the proportions being by weight and based on theclean wool, is employed. It is to be noted that in floor coveringshaving low twist piles, cross-bred wools or blends of wool containing ahigh percentage of cross-bred wools are undesirable since they do notfill out and cover as well as carpet wools and, due to their softness,crush very readily.

The invention is not restricted to the pile yarns of the precise weightand-construction set forth in the examples.- The pile yarn can be formedof more than two singles yarns and the singles twist can be greater orsmaller than that of the examples. In all cases the plying twist issufficient to give a knobby or curly appearance or texture to the cutpile resultingtherefrom. Preferably, the twists in the respectivesingles yarns are in the same direction and the plying twist is in thedirection opposite to the direction of the singles twist.

Inthis specification, the terms hard twist and high twist, or similarterms, are used as is well known in the art to define that amount oftwist in a pile yarn which is sufficient to give a knobby or curlyappearance or texture in a cut pile formed therefrom.

Hereinafter are set forth several illustrative examples of yarnconstructions which can be used in accordance with this invention inconnection with frieze carpets:

Sin les in les Plyed Pived Twist Weight Twist Weight 'lwo-plv Frieze.175 207 350 .456 Three-Div Frieze 175 148 250 503 Two-ply Knobby Yarn200 148 296 in excess of the minimum amount, such as up to 100%, byweight, of the wool, can be used with success in this process.

The addition of moisture to the yarn prior to steaming is preferablyaccomplished by the method shown in the specific examples, though itwill be apparent to a person skilled in the art that other procedurescan be used.

The high twist is set by steaming at high moisture levels whereby themoisture content in the yarn is maintained during steaming at at least30% or higher. In the preferred embodiment, this is accomplished bysubjecting the highly twisted yarn containing at least 30% moisture tosaturated steam. One procedure which has been found satisfactory forproducing saturated steam, using present equipment, is to desuperheatthe steam after throttling it down from a high pressure, such as 80pounds per square inch gauge pressure, to 2 pounds per square inch gaugepressure before introducing it into the cottage steamer.

The usual practices for stock dyeing wool for carpets and rugs utilizeso-called acid or chrome dyes, which leave the wool in an acid state, i.e. the wool has a pH of from 2 to 5. Experimental research has shownthat when the yarn is rendered approximately neutral by adjusting the pHof the yarn to between 6 and 8, or even alkaline by adjusting the pH upto 10, the setting reaction is improved and proceeds more rapidly thanwhen the pH is from 2 to 5. The pH adjustment of the yarn can beaccomplished by various methods, such as treatment with aqueoussolutions of alkaline substances followed by rinsing with water toremove excess materials. The pH adjustment can be the final step of thedyeing operation. It can be carried out during yarn manufacture or itcan be accomplished after the yarn has been spun. In the latterinstance, it can be part of an alkaline scouring designed to brightenthe color and remove oil and grease. Sodium carbonate is the preferredalkaline substance, and the concentration thereof in the aqueoussolution depends on the pH of the wool to be neutralized. In general,aqueous solutions containing 0.25% to 1% of'sodium carbonate can beused, though other concentrations can be used.

In neutral wool dyeing processes, it is customary to conclude the dyeingoperation by the addition of sumcient acid to exhaust the dye. Thisproduces a wool which contains suflicient acid to inh bit setting. Thus,even when the wool is dyed by the so-called neutral dyeing processes,the pH of the yarn resulting therefrom should be adjusted, ashereinbefore set forth.

The t me of the steaming operation can vary within limits depending, inpart, on the wools constituting the yarn, the pH of the wools, the

-moisture content, and the temperature, and can be determined by simpleempirical experiment. In no case should the steaming operation be forsuch period of time that will seriously deleteriously affect the yarn.

Yarn resulting from Example I possesses improved twist fastness toaqueous treatments and commercial shampooing as compared to the yarnsresulting from the prior art procedures, i. e. steaming at low moisturelevels. The treatment with formaldehyde, as disclosed in Example II,improves the twist fastness so that the carpet will successfullywithstand multiple commercial shamnooing without serious loss of twist.Additionally, the treatment with the formaldehyde enables a high levelof twist-set fastness to be obtained with a reduced time of wet steamingand therefore minimizes the loss of abrasive wear resistance caused bylong periods of steaming.

The invention is not restricted to the specific formaldehyde solution orthe time and temperature conditions under which the steamed yarn istreated in Example II. The concentration of the aqueous solution offormaldehyde may vary. For example, an aqueous solution containing aslow as 0.1% of formaldehyde and as high as 10% of formaldehyde has beenfound to give satisfactory results. The temperature of the formaldehydetreatment depends on the concentration of the formaldehyde. tion, thelower the temperature. Thus, for example, when the formaldehyde solutioncontains 0.1% of formaldehyde, satisfactory results are obtained with atemperature of 212 F. Likewise, the period of immersion varies with theconcentration and temperature and may be, depending on the temperatureand concentration, a few minutes to several hours. In all cases, theformaldehyde reaction condition depends also on the type of wool, thesteaming conditions, and the fastness of the dyes used to theformaldehyde.

Instead of an aqueous solution of formaldehyde, monomeric formaldehydegas, which would dissolve in the moisture content in the yarn, can beused. Alternatively, the yarn can be impregnated with a substance thatyields formaldehyde upon heating.

Though formaldehyde is preferred, manifestly ployed. Acetaldehyde andglyoxal are illustrative examples of additional aldehydes which can beused.

If desired, an acid or acid salt catalyst can be used in conjunctionwith the aldehyde treatments.

Wool that has been steamed in a neutral condition at a high moisturelevel in accordance'with the instant invention reacts more completelywith formaldehyde than does wool steamed in an acid condition at lowmoisture levels. In one instance,

' yarn steamed equal lengths of time by the two methods and treated withformaldehyde in the same manner analyzed 0.3% combined formaldehyde whensteamed in the normal fashion and 1% combined formaldehyde when steamedin the neutral wet manner.

Though the invention has been described specifically in connection withfloor coverin s having cut piles it is'to be understood that theinvention is not restricted thereto. In general, the invention isapplicable to-pile yarns which are to constitute cut pile in fabrics subected to hard wear, such as floor coverings, upholstery fabrics. etc.

Since it is obvious that various changes and modifications may be madein the above description without departing from the nature of spiritthereof, this invention is not restricted thereto except as set forth inthe appended claims.

I claim:

1. A process for preparing highly twisted wool yarns which when formedinto a cut pile of a pile fabric intended for hard wear the twist willbe substantially fast to aqueous treatment, which comprises forming ahighly twisted stock dyed wool yarn in which the pores, theintermicellar spaces and the micellar structure of the wool are at leastsaturated with moisture, setting the twist by steaming said yarn, duringthe steaming treatment maintaining the moisture content in the yarn atat least that which saturates the pores, the intermicellar spaces andthe micellar struc- The higher the concentrature of the wool, andreacting the steamed yarn with an aldehyde.

2. A process for preparing highly twisted wool yarns which when formedinto a cut pile of a pile fabric intended for hard wear the twist willbe substantially fast to aqueous treatment, which comprises forming ahighly twisted stock dyed wool yarn having a pH of from 6 to 10 and inwhich the pores, the intermicellar spaces and the micellar structure ofthe wool are at least saturated with moisture, setting the twist bysteaming said yarn, during the steaming treatment maintaining themoisture content in the yarn at at least that which saturates the pores,the intermicellar spaces and the micellar structure of the wool, andreacting the steamed yarn with an aldehyde.

3. A process for preparing highly twisted wool yarns which when formedinto a cut pile of a pile fabric intended for hard wear the twist willbe substantially fast to aqueous treatment, which comprises forming ahighly twisted stock dyed wool yarn containing at least 30% by weight ofmoisture, setting the twist by steaming said yarn, maintaining themoisture content in the yarn at at least 30% during the steamingtreatment,

and reacting the steamed yarn with an aldehyde.

4. A process for preparing highly twisted wool yarns which when formedinto a cut pile of a pile fabric intended for hard wear the twist willbe substantially fast to aqueous treatment, which comprises forming ahighly twisted stock dyed wool yarn having a pH of from 6 to 10 andcontaining at least 30% by weight of moisture, setting the twist bysteaming said yarn, maintaining the moisture content in the yarn at atleast 30% during the steaming treatment, and reacting the steamed yarnwith an aldehyde.

5. A process for preparing highly twisted wool yarns which when formedinto a cut pile of a pile fabric intended for hard wear the twist willbe substantially fast to aqueous treatment, which comprises forming ahighly twisted plied yarn of stock dyed wool having a pH in theneighborhood of 4.2, adjusting the pH of said yarn to approximately 6.5,reducing the moisture content of said yarn to 35%, and steaming saidyarn in a closed steamer with saturated steam to set said twist andsoaking the steamed yarn in a 4% aqueous solution of formaldehyde at 100F. for 3 hours.

ROBERT C. ALLISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,090,971 Cilley Mar. 24, 19141,210,394 Anders Jan. 2, 1917 1,815,027 Murch July 14, 1931 2,058,948Blumenthal Oct. 27, 1936 2,212,744 Masland Aug. 27, 1940 2,290,253Schneider July 21, 1942 2,346,126 Lessig Apr. 11, 1944 OTHER REFERENCES"Journal Textile Institute, Sept. 1943,-pages T -T76.

Textile Fibers, by Matthews, fourth edition, 1924, John Wiley and Sons,New York.

"Journal of Society of Dyers & Colourists, Sept. 1936, pages 335-346.

